mirror of
https://github.com/seaweedfs/seaweedfs.git
synced 2026-09-11 17:10:40 +02:00
Chris Lu
53fe128511
A format adapter reduces one container format to three things the core understands: extent sizes, an alignment quantum, and an opaque payload. Capabilities beyond identity (Indexer, SidecarIndexer, Viewer) are discovered by type assertion. The layout persists in one compact extended attribute keyed by extent sizes rather than chunk ids, so it survives chunk manifest folding, and the Cutter turns it into upload chunk boundaries clamped by maxMB and the align quantum. The formattest kit holds every adapter to no-panic parsing of truncated input.
84 lines
2.5 KiB
Go
84 lines
2.5 KiB
Go
// Package format maps the internal structure of container file formats onto
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// storage chunk boundaries.
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//
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// An adapter translates one format into three things the core understands: a
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// list of extent sizes, an alignment quantum, and an opaque payload. Adapters
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// never see chunks, file ids, or authorization; the core never learns what an
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// MPEG-TS packet or a parquet row group is.
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package format
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import (
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"context"
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"errors"
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"io"
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"net/url"
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)
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// LayoutKey is the filer Extended key holding the encoded Layout. The
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// x-seaweedfs- prefix keeps it out of HTTP response headers.
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const LayoutKey = "x-seaweedfs-format-layout"
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// ErrNoSuchView reports that a view request addresses nothing servable; the
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// server answers 404.
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var ErrNoSuchView = errors.New("no such view")
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// Layout describes how a file's structure maps to byte extents.
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type Layout struct {
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Format string // adapter name
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ExtentSizes []int64 // extent lengths in file order; they sum to the file size
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Align int64 // quantum for cutting inside an oversized extent; 1 cuts anywhere
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Payload []byte // adapter-owned metadata, opaque to the core
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}
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// Hint carries the cheap identification signals available to Sniff.
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type Hint struct {
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Name string
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ContentType string
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Size int64
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Head []byte
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Tail []byte
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}
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// Format is the mandatory adapter identity. Capabilities beyond it are
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// discovered by type assertion.
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type Format interface {
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Name() string
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Sniff(h Hint) bool
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}
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// Indexer derives a Layout from the complete stored bytes.
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type Indexer interface {
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Index(ctx context.Context, r io.ReaderAt, size int64) (*Layout, error)
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}
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// SidecarIndexer derives a Layout from an external index document supplied at
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// ingest, before the media bytes arrive.
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type SidecarIndexer interface {
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IndexSidecar(sidecar []byte) (*Layout, error)
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}
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// Object is everything a Viewer may know about the file it serves.
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type Object struct {
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Name string
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Size int64
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Layout *Layout
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}
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// ViewRequest carries the request parameters of a ?view= request.
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type ViewRequest struct {
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Query url.Values
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}
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// ViewPlan tells the server what to serve. The server executes it on the
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// normal streaming path; adapters stay pure functions of request and layout.
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type ViewPlan struct {
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ContentType string
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Body []byte // rendered document; when nil, stream Extent instead
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Extent int
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}
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// Viewer answers ?view= requests.
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type Viewer interface {
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View(req ViewRequest, obj Object) (*ViewPlan, error)
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}
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